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1.
Oman Med J ; 35(2): e110, 2020 Mar.
Article in English | MEDLINE | ID: mdl-32257419

ABSTRACT

OBJECTIVES: Anabolic-androgenic steroids (AAS) have been used internationally for enhancing physical appearance and performance despite their significant side effects. We sought to identify the prevalence of AAS use and its different risk factors among gym users in Riyadh, Saudi Arabia. METHODS: A cross-sectional survey was distributed among gym users across 20 gyms in Riyadh. The cluster sampling technique was used to represent the four regions of Riyadh (North, South, East, and West). Univariate and multivariate analyses were performed to identify the factors associated with AAS. RESULTS: Out of 482 participants, 29.3% reported using AAS. The mean age of the study participants was 27.2±6.9 years, 61.0% were single, 67.1% were educated, 35.5% were government employees, and 31.1% were students. The use of AAS was more prevalent among gym members who practiced weightlifting (45.5%), were employed in the private sector (35.8%), and aged > 25 years old (53.3%). Multiple logistic regression showed that the most significant factors associated with the use of AAS among gym members were: weightlifting, using supplementary vitamins or minerals, following special diets, knowing individuals who used AAS, and being offered AAS. CONCLUSIONS: Our study provides clear evidence that the lifetime prevalence of AAS use is high among male gym members in Riyadh with modifiable risk factors. The results could help public health policymakers to take the necessary measures to alleviate the potential negative implications of AAS use at the community level.

2.
Saudi Pharm J ; 27(2): 254-263, 2019 Feb.
Article in English | MEDLINE | ID: mdl-30766438

ABSTRACT

Recreational use of anabolic-androgenic steroids (AAS) is a growing worldwide public health concern. However, studies assessing the level of awareness and knowledge of its effects on health are fairly limited, especially in developing countries, including Saudi Arabia. This community-based cross-sectional study was conducted to assess knowledge, attitudes and practices among male gym members toward AAS in Riyadh (Saudi Arabia) from March to October 2016. Twenty gyms were randomly selected from four different geographical regions (clusters) within Riyadh. In total, 482 participants responded to the self-administered anonymous questionnaire, which covered socio-demographic data, data assessing knowledge, attitude and behavior related to AAS use. The mean (±standard deviation) age of study participants was 27.2 (±6.9) years. Among these, 29.3% of participants reported having used AAS, while the majority (53.5%) reported hearing of AAS use, mostly through friends. Most study participants reported awareness of the effects of AAS on muscle mass, body weight and muscles strength (53.2%, 51.1% and 45.5%, respectively). In contrast, a higher proportion of study participants were unaware of the side-effects of AAS use. A high proportion of study participants (43.2%) reported that they had been offered AAS and 68.7% believed that AAS are easily accessible. Most of the gym users (90.1%) reported never having used any narcotics or psychoactive drugs. Regression analysis revealed that use of anabolic-androgenic steroids is significantly associated with "weight lifting practice" OR [95%CI] = 1.9[1.02 - 3.61], P = 0.044; "using supplementary vitamins, OR [95%CI] = 7.8[4.05 - 15.03], P < 0.0001, knowing anyone using anabolic-androgenic steroids' OR [95%CI] = 7.5[3.78 - 14.10], P < 0.0001, and someone advised Gym users to take anabolic-androgenic steroids" OR [95%CI] = 2.26[1.23 - 4.14], P < 0.008. Our findings suggest that the level of awareness regarding the possible side-effects of AAS is fairly limited. Thus, efforts directed toward educating the public and limiting access to AAS as well as health policy reforms are crucial to reduce future negative implications of AAS use.

3.
Drug Alcohol Depend ; 161: 298-306, 2016 Apr 01.
Article in English | MEDLINE | ID: mdl-26925704

ABSTRACT

BACKGROUND: There is currently no pharmacological treatment approved for cannabis dependence. In this proof of concept study, we assessed the feasibility/effects of fixed and self-titrated dosages of Sativex (1:1, Δ(9)-tetrahydrocannabinol (THC)/cannabidiol (CBD)) on craving and withdrawal from cannabis among nine community-recruited cannabis-dependent subjects. METHODS: Participants underwent an 8-week double-blind placebo-controlled trial (an ABACADAE design), with four smoke as usual conditions (SAU) (A) separated by four cannabis abstinence conditions (B-E), with administration of either self-titrated/fixed doses of placebo or Sativex (up to 108 mg THC/100 mg CBD). The order of medication administration during abstinence conditions was randomized and counterbalanced. Withdrawal symptoms and craving were assessed using the Cannabis Withdrawal Scale (CWS), Marijuana Withdrawal Checklist (MWC) and Marijuana Craving Questionnaire (MCQ). Medication use was assessed during the study by means of self-reports, vial weight control, toxicology and metabolite analysis. Cannabis use was assessed by means of self-reports. RESULTS: High fixed doses of Sativex were well tolerated and significantly reduced cannabis withdrawal during abstinence, but not craving, as compared to placebo. Self-titrated doses were lower and showed limited efficacy as compared to high fixed doses. Participants reported a significantly lower "high" following Sativex or placebo as compared to SAU conditions. Cannabis/medication use along the study, as per self-reports, suggests compliance with the study conditions. CONCLUSIONS: The results found in this proof of concept study warrant further systematic exploration of Sativex as a treatment option for cannabis withdrawal and dependence.


Subject(s)
Cannabis/adverse effects , Craving/drug effects , Marijuana Abuse/drug therapy , Plant Extracts/administration & dosage , Substance Withdrawal Syndrome/drug therapy , Adult , Cannabidiol , Double-Blind Method , Dronabinol , Drug Combinations , Female , Humans , Male , Marijuana Smoking , Middle Aged , Plant Extracts/therapeutic use , Substance-Related Disorders/drug therapy , Treatment Outcome , Young Adult
4.
Psychopharmacology (Berl) ; 233(10): 1823-8, 2016 05.
Article in English | MEDLINE | ID: mdl-26864774

ABSTRACT

RATIONALE: The endocannabinoid system is composed of endocannabinoids (such as anandamide), their target receptors (CB1 and CB2 receptors, CB1Rs and CB2Rs), the enzymes that degrade them (fatty-acid-amide-hydrolase (FAAH) for anandamide), and an endocannabinoid transporter. FAAH inhibition has been recently identified as having a critical involvement in behaviors related to nicotine addiction and has been shown to reduce the effect of nicotine on the mesolimbic dopaminergic system via CB1R and peroxisome proliferator-activated receptor alpha (PPARα). Thus, inhibition of FAAH may represent a novel strategy for smoking cessation, but its mechanism of action on relapse to nicotine seeking is still unknown. OBJECTIVE: The study aims to explore the mechanism of action of the inhibitor of FAAH activity, URB597, on relapse to nicotine seeking by evaluating the effect of the CB1R, CB2R, and PPARα antagonists on the attenuating effect of URB597 on cue-induced reinstatement of nicotine seeking in rats. RESULTS: URB597 reduced cue-induced reinstatement of nicotine seeking, an effect that was reversed by the CB1R antagonist rimonabant, but not by the CB2R or PPARα antagonists AM630 and MK886, respectively. CONCLUSIONS: These results indicate that URB597 reduces cue-induced reinstatement in rats through a CB1 receptor-dependent mechanism, and not via CB2R or PPARα. Since FAAH inhibition represent a novel and promising strategy for tobacco smoking cessation, dissecting how it produces its action may lead to a better understanding of the neurobiological mechanisms underlying nicotine addiction.


Subject(s)
Amidohydrolases/antagonists & inhibitors , Benzamides/pharmacology , Cannabinoid Receptor Antagonists/pharmacology , Carbamates/pharmacology , Drug-Seeking Behavior/drug effects , Nicotine/administration & dosage , Receptor, Cannabinoid, CB1/antagonists & inhibitors , Tobacco Use Disorder/drug therapy , Amidohydrolases/metabolism , Animals , Arachidonic Acids/metabolism , Cues , Endocannabinoids/metabolism , Male , PPAR alpha/metabolism , Piperidines/pharmacology , Polyunsaturated Alkamides/metabolism , Pyrazoles/pharmacology , Rats , Rats, Long-Evans , Receptor, Cannabinoid, CB1/metabolism , Receptor, Cannabinoid, CB2/metabolism , Rimonabant
5.
Neuropsychopharmacology ; 41(6): 1513-20, 2016 May.
Article in English | MEDLINE | ID: mdl-26442600

ABSTRACT

Varenicline, a nicotinic partial agonist, is the most effective treatment for tobacco use disorder. However, its mechanism of action is still unclear and may involve stimulating dopaminergic transmission. Here we used PET imaging with [(11)C]-(+)-PHNO to explore for the first time the impact of varenicline on dopamine transmission in the D2-rich striatum and D3-rich extra-striatal regions and its relationship with craving, withdrawal and smoking. Eleven treatment-seeking smokers underwent two PET scans with [(11)C]-(+)-PHNO, each following 12-h overnight smoking abstinence both prior to receiving varenicline and following 10-11 days of varenicline treatment (ie, at steady-state drug levels). Subjective measures of craving and urges to smoke were also assessed on the days of the PET scans. Varenicline treatment significantly reduced [(11)C]-(+)-PHNO binding in the dorsal caudate (p=0.008) and reduced some craving measures. These findings provide the first evidence that varenicline is able to increase DA levels in the human brain, a factor that may contribute to its therapeutic efficacy.


Subject(s)
Brain Chemistry/drug effects , Dopamine/analysis , Smoking/therapy , Varenicline/pharmacology , Adult , Brain/drug effects , Brain/physiopathology , Brain Chemistry/physiology , Dopamine/physiology , Female , Humans , Magnetic Resonance Imaging , Male , Neuroimaging , Positron-Emission Tomography , Receptors, Dopamine D2/drug effects , Receptors, Dopamine D2/physiology , Receptors, Dopamine D3/drug effects , Receptors, Dopamine D3/physiology , Smoking/physiopathology , Tobacco Use Cessation Devices
6.
Front Psychiatry ; 6: 41, 2015.
Article in English | MEDLINE | ID: mdl-25859226

ABSTRACT

Several lines of evidence have shown that the endogenous cannabinoids are implicated in several neuropsychiatric diseases. Notably, preclinical and human clinical studies have shown a pivotal role of the cannabinoid system in nicotine addiction. The CB1 receptor inverse agonist/antagonist rimonabant (also known as SR141716) was effective to decrease nicotine-taking and nicotine-seeking in rodents, as well as the elevation of dopamine induced by nicotine in brain reward area. Rimonabant has been shown to improve the ability of smokers to quit smoking in randomized clinical trials. However, rimonabant was removed from the market due to increased risk of psychiatric side-effects observed in humans. Recently, other components of the endogenous cannabinoid system have been explored. Here, we present the recent advances on the understanding of the role of the different components of the cannabinoid system on nicotine's effects. Those recent findings suggest possible alternative ways of modulating the cannabinoid system that could have implication for nicotine dependence treatment.

7.
BMJ Case Rep ; 20132013 Aug 07.
Article in English | MEDLINE | ID: mdl-23925680

ABSTRACT

Naltrexone is a first-line treatment for alcohol use disorders in North America and Europe. It was prescribed to a 63-year-old patient in order to help control amounts of alcohol consumed per drinking occasion. The patient experienced a paradoxical, but consistent side effect of feeling inebriated each time he took naltrexone. In order to investigate this phenomenon we administered naltrexone and a placebo in a randomised double-blind fashion. The patient exhibited a 'high-like' response to all placebo capsules and a decrease in the subjectively perceived euphoria shortly after ingestion of naltrexone. Given that this placebo effect could be mediated via opioid receptors we suggest that this case illustrates the ability of naltrexone to eliminate the placebo effect. This feature of naltrexone, upon further investigation, might be used in randomised clinical trials in addition to or as an alternative to a placebo.


Subject(s)
Euphoria/drug effects , Naltrexone/adverse effects , Placebo Effect , Humans , Male , Middle Aged
8.
J Psychopharmacol ; 27(6): 564-71, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23427192

ABSTRACT

Multiple studies suggest a pivotal role of the endocannabinoid system in the regulation of the reinforcing effects of various substances of abuse. Different approaches have been used to modulate endocannabinoid neurotransmission including the use of endogenous cannabinoid anandamide reuptake inhibitors. Previously, the effects of one of them, N-(4-hydroxyphenyl)-arachidonamide (AM404), have been explored in rodents trained to self-administer ethanol and heroin, producing some promising results. Moreover, AM404 attenuated the development and reinstatement of nicotine-induced conditioned place preference (CPP). In this study, we used the nicotine intravenous self-administration procedure to assess the effects of intraperitoneal administration of 0, 1, 3 and 10 mg/kg AM404 on nicotine-taking and food-taking behaviors under fixed-ratio and progressive-ratio schedules of reinforcement, as well as on reinstatement of nicotine-seeking induced by nicotine priming and by presentation of nicotine-associated cues. The ability of AM404 to produce place preference was also evaluated. AM404 did not produce CPP and did not modify nicotine-taking and food-taking behaviors. In contrast, AM404 dose-dependently attenuated reinstatement of nicotine-seeking behavior induced by both nicotine-associated cues and nicotine priming. Our results indicate that AM404 could be a potential promising therapeutic option for the prevention of relapse to nicotine-seeking in abstinent smokers.


Subject(s)
Arachidonic Acids/pharmacology , Conditioning, Psychological/drug effects , Drug-Seeking Behavior/drug effects , Nicotine/administration & dosage , Animals , Arachidonic Acids/administration & dosage , Cues , Dose-Response Relationship, Drug , Feeding Behavior/drug effects , Injections, Intraperitoneal , Male , Rats , Rats, Long-Evans , Reinforcement Schedule , Secondary Prevention , Self Administration
9.
PLoS One ; 7(1): e29900, 2012.
Article in English | MEDLINE | ID: mdl-22291896

ABSTRACT

Over the last decade there have been significant advances in the discovery and understanding of the cannabinoid system along with the development of pharmacologic tools that modulate its function. Characterization of the crosstalk between nicotine addiction and the cannabinoid system may have significant implications on our understanding of the neurobiological mechanisms underlying nicotine dependence. Two types of cannabinoid receptors (CB1 and CB2) have been identified. CB1 receptors are expressed in the brain and modulate drug taking and drug seeking for various drugs of abuse, including nicotine. CB2 receptors have been recently identified in the brain and have been proposed to play a functional role in mental disorders and drug addiction. Our objective was to explore the role of CB2 receptors on intravenous nicotine self administration under two schedules of reinforcement (fixed and progressive ratio) and on nicotine seeking induced by nicotine priming or by nicotine associated cues. For this, we evaluated the effects of various doses of the selective CB2 antagonist AM630 (1.25 to 5 mg/kg) and CB2 agonist AM1241 (1 to 10 mg/kg) on these behavioral responses in rats. Different groups of male Long Evans rats were trained to lever press for nicotine at a unit dose of 30 µg/kg/infusion. Subsequently, animals were randomized using a Latin-square design and injected with either AM1241 or AM630 using a counterbalanced within subject design. Administration of the CB2 ligands did not affect either nicotine-taking nicotine-seeking behavior. Our results do not support the involvement of CB2 receptors in nicotine-taking or nicotine-seeking behavior.


Subject(s)
Drug-Seeking Behavior/drug effects , Indoles/pharmacology , Nicotine/administration & dosage , Tobacco Use Disorder/psychology , Animals , Behavior, Animal/drug effects , Cannabinoids/pharmacology , Conditioning, Operant , Drug-Seeking Behavior/physiology , Injections, Intravenous , Male , Rats , Rats, Long-Evans , Receptor, Cannabinoid, CB2/agonists , Receptor, Cannabinoid, CB2/antagonists & inhibitors , Recurrence , Reinforcement, Psychology , Self Administration , Substrate Specificity/drug effects , Tobacco Use Disorder/pathology
10.
Behav Brain Res ; 230(1): 34-9, 2012 Apr 21.
Article in English | MEDLINE | ID: mdl-22326373

ABSTRACT

The ability to examine genetically engineered mice in a chronic intravenous (IV) nicotine self-administration paradigm will be a powerful tool for investigating the contribution of specific genes to nicotine reinforcement and more importantly, to relapse behavior. Here we describe a reliable model of nicotine-taking and -seeking behavior in male C57BL/6J mice without prior operant training or food restriction. Mice were allowed to self-administer either nicotine (0.03mg/kg/infusion) or saline in 2-h daily sessions under fixed ratio 1 (FR1) followed by FR2 schedules of reinforcement. In the nicotine group, a dose-response curve was measured after the nose-poke behavior stabilized. Subsequently, nose-poke behavior was extinguished and ability of cue presentations, priming injections of nicotine, or intermittent footshock to reinstate responding was assessed in both groups. C57BL/6J mice given access to nicotine exhibited high levels of nose-poke behavior and self-administered a high number of infusions as compared to mice given access to saline. After this acquisition phase, changing the unit-dose of nicotine resulted in a flat dose-response curve for nicotine-taking and subsequently reinstatement of nicotine-seeking behavior was achieved by both nicotine-associated light cue presentation and intermittent footshock. Nicotine priming injections only triggered significant reinstatement on the second consecutive day of priming. In contrast, mice previously trained to self-administer saline did not increase their responding under those conditions. These results demonstrate the ability to produce nicotine-taking and nicotine-seeking behavior in naive C57BL/6J mice without both prior operant training and food restriction. Future work will utilize these models to evaluate nicotine-taking and relapsing behavior in genetically-altered mice.


Subject(s)
Conditioning, Operant/physiology , Food Deprivation/physiology , Nicotine/administration & dosage , Nicotinic Agonists/administration & dosage , Reinforcement, Psychology , Analysis of Variance , Animals , Cues , Dose-Response Relationship, Drug , Electroshock/adverse effects , Exploratory Behavior/drug effects , Extinction, Psychological/drug effects , Male , Mice , Mice, Inbred C57BL , Reinforcement Schedule , Self Administration
11.
Addict Biol ; 17(1): 47-61, 2012 Jan.
Article in English | MEDLINE | ID: mdl-21521420

ABSTRACT

The cannabinoid system appears to play a critical facilitative role in mediating the reinforcing effects of nicotine and relapse to nicotine-seeking behaviour in abstinent subjects based on the actions of cannabinoid (CB) receptor antagonists. However, the effects of CB receptor stimulation on nicotine self-administration and reinstatement have not been systematically studied. Here, we studied the effects of WIN 55,212-2, a CB1/2 agonist, on intravenous nicotine self-administration under fixed-ratio (FR) and progressive-ratio (PR) schedules of reinforcement in rats. The effects of WIN 55,212-2 on responding for food under similar schedules were also studied. In addition, the effects of WIN 55,212-2 on nicotine- and cue-induced reinstatement of nicotine seeking were also studied, as well as the effects of WIN 55,212-2 on nicotine discrimination. WIN 55,212-2 decreased nicotine self-administration under the FR schedule. However, co-administration of WIN 55,212-2 with nicotine decreased responding for food, which suggests that this effect was non-selective. In contrast, WIN 55,212-2 increased both nicotine self-administration and responding for food under the PR schedule, produced dose-dependent reinstatement of nicotine seeking, and enhanced the reinstatement effects of nicotine-associated cues. Some of these effects were reversed by the CB1 antagonist rimonabant, but not by the CB2 antagonist AM630. In the drug discrimination tests between saline and 0.4 mg/kg nicotine, WIN 55,212-2 produced no nicotine-like discriminative effects but significantly potentiated discriminative stimulus effects of nicotine at the low dose through a CB1-receptor-dependent mechanism. These findings indicate that cannabinoid CB1-receptor stimulation increases the reinforcing effects of nicotine and precipitates relapse to nicotine-seeking behaviour in abstinent subjects. Thus, modulating CB1-receptor signalling might have therapeutic value for treating nicotine dependence.


Subject(s)
Motivation/drug effects , Nicotine/administration & dosage , Receptor, Cannabinoid, CB1/antagonists & inhibitors , Tobacco Use Disorder , Analgesics, Opioid/pharmacology , Animals , Behavior, Addictive/chemically induced , Behavior, Animal , Benzoxazines/pharmacology , Conditioning, Operant/drug effects , Cues , Discrimination, Psychological/drug effects , Dose-Response Relationship, Drug , Extinction, Psychological/drug effects , Feeding Behavior/drug effects , Male , Morpholines/pharmacology , Motor Activity/drug effects , Naphthalenes/pharmacology , Piperidines/pharmacology , Pyrazoles/pharmacology , Rats , Rats, Long-Evans , Rats, Sprague-Dawley , Reinforcement, Psychology , Rimonabant , Self Administration/statistics & numerical data
12.
Br J Pharmacol ; 165(8): 2539-48, 2012 Apr.
Article in English | MEDLINE | ID: mdl-21557729

ABSTRACT

BACKGROUND AND PURPOSE: The fatty acid amide hydrolase inhibitor URB597 can reverse the abuse-related behavioural and neurochemical effects of nicotine in rats. Fatty acid amide hydrolase inhibitors block the degradation (and thereby magnify and prolong the actions) of the endocannabinoid anandamide (AEA), and also the non-cannabinoid fatty acid ethanolamides oleoylethanolamide (OEA) and palmitoylethanolamide (PEA). OEA and PEA are endogenous ligands for peroxisome proliferator-activated receptors alpha (PPAR-α). Since recent evidence indicates that PPAR-α can modulate nicotine reward, it is unclear whether AEA plays a role in the effects of URB597 on nicotine reward. EXPERIMENTAL APPROACH: A way to selectively increase endogenous levels of AEA without altering OEA or PEA levels is to inhibit AEA uptake into cells by administering the AEA transport inhibitor N-(4-hydroxyphenyl)-arachidonamide (AM404). To clarify AEA's role in nicotine reward, we investigated the effect of AM404 on conditioned place preference (CPP), reinstatement of abolished CPP, locomotor suppression and anxiolysis in an open field, and dopamine elevations in the nucleus accumbens shell induced by nicotine in Sprague-Dawley rats. KEY RESULTS: AM404 prevented the development of nicotine-induced CPP and impeded nicotine-induced reinstatement of the abolished CPP. Furthermore, AM404 reduced nicotine-induced increases in dopamine levels in the nucleus accumbens shell, the terminal area of the brain's mesolimbic reward system. AM404 did not alter the locomotor suppressive or anxiolytic effect of nicotine. CONCLUSIONS AND IMPLICATIONS: These findings suggest that AEA transport inhibition can counteract the addictive effects of nicotine and that AEA transport may serve as a new target for development of medications for treatment of tobacco dependence. LINKED ARTICLES: This article is part of a themed section on Cannabinoids in Biology and Medicine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-8. To view Part I of Cannabinoids in Biology and Medicine visit http://dx.doi.org/10.1111/bph.2011.163.issue-7.


Subject(s)
Arachidonic Acids/antagonists & inhibitors , Arachidonic Acids/therapeutic use , Behavior, Addictive/drug therapy , Nicotine/pharmacology , Nucleus Accumbens/drug effects , Polyunsaturated Alkamides/antagonists & inhibitors , Animals , Arachidonic Acids/pharmacology , Arachidonic Acids/physiology , Behavior, Addictive/physiopathology , Behavior, Animal/drug effects , Conditioning, Psychological/physiology , Dopamine/metabolism , Dronabinol/pharmacology , Endocannabinoids , Male , Motor Activity/drug effects , Nicotinic Agonists/pharmacology , Nucleus Accumbens/physiology , Rats , Rats, Sprague-Dawley , Reward
13.
Int J Neuropsychopharmacol ; 15(9): 1265-74, 2012 Oct.
Article in English | MEDLINE | ID: mdl-21939589

ABSTRACT

Effects of varenicline (Champix), a nicotinic partial agonist, were evaluated on subjective effects of nicotine (drug discrimination), motivation for nicotine taking (progressive-ratio schedule of intravenous nicotine self-administration) and reinstatement (cue-induced reinstatement of previously extinguished nicotine-seeking behaviour). Effects on motor performance were assessed in rats trained to discriminate nicotine (0.4 mg/kg) from saline under a fixed-ratio (FR 10) schedule of food delivery and in rats trained to respond for food under a progressive-ratio schedule. At short pretreatment times (5-40 min), varenicline produced full or high levels of partial generalization to nicotine's discriminative-stimulus effects and disrupted responding for food, while there were low levels of partial generalization and no disruption of responding for food at 2- or 4-h pretreatment times. Varenicline (1 and 3 mg/kg, 2-h pretreatment time) enhanced discrimination of low doses of nicotine and to a small extent decreased discrimination of the training dose of nicotine. It also dose-dependently decreased nicotine-taking behaviour, but had no effect on food-taking behaviour under progressive-ratio schedules. Finally, varenicline significantly reduced the ability of a nicotine-associated cue to reinstate extinguished nicotine-seeking behaviour. The ability of varenicline to reduce both nicotine-taking and nicotine-seeking behaviour can contribute to its relatively high efficacy in treating human smokers.


Subject(s)
Benzazepines/pharmacology , Cues , Drug-Seeking Behavior/drug effects , Quinoxalines/pharmacology , Tobacco Use Disorder/drug therapy , Animals , Conditioning, Operant/drug effects , Data Interpretation, Statistical , Discrimination, Psychological/drug effects , Dose-Response Relationship, Drug , Feeding Behavior/drug effects , Male , Motivation/drug effects , Nicotine/pharmacology , Rats , Rats, Long-Evans , Rats, Sprague-Dawley , Reinforcement Schedule , Self Administration , Tobacco Use Disorder/psychology , Varenicline
14.
Neuropsychopharmacology ; 37(3): 685-96, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22030716

ABSTRACT

Since cloning of the dopamine receptor D4 (DRD4), its role in the brain has remained unclear. It has been reported that polymorphism of the DRD4 gene in humans is associated with reactivity to cues related to tobacco smoking. However, the role of DRD4 in animal models of nicotine addiction has seldom been explored. In our study, male Long-Evans rats learned to intravenously self-administer nicotine under a fixed-ratio (FR) schedule of reinforcement. Effects of the selective DRD4 antagonist L-745,870 were evaluated on nicotine self-administration behavior and on reinstatement of extinguished nicotine-seeking behavior induced by nicotine-associated cues or by priming injections of nicotine. L-745,870 was also tested on reinstatement of extinguished food-seeking behavior as a control. In addition, the selective DRD4 agonist PD 168,077 was tested for its ability to reinstate extinguished nicotine-seeking behavior. Finally, L-745,870 was tested in Sprague Dawley rats trained to discriminate administration of 0.4 mg/kg nicotine from vehicle under an FR schedule of food delivery. L-745,870 significantly attenuated reinstatement of nicotine-seeking induced by both nicotine-associated cues and nicotine priming. In contrast, L-745,870 did not affect established nicotine self-administration behavior or reinstatement of food-seeking behavior induced by food cues or food priming. L-745,870 did not produce nicotine-like discriminative-stimulus effects and did not alter discriminative-stimulus effects of nicotine. PD 168,077 did not reinstate extinguished nicotine-seeking behavior. As DRD4 blockade by L-745,870 selectively attenuated both cue- and nicotine-induced reinstatement of nicotine-seeking behavior, without affecting cue- or food-induced reinstatement of food-seeking behavior, DRD4 antagonists are potential therapeutic agents against tobacco smoking relapse.


Subject(s)
Behavior, Animal/drug effects , Drug-Seeking Behavior/drug effects , Extinction, Psychological/drug effects , Nicotine/administration & dosage , Receptors, Dopamine D4/antagonists & inhibitors , Animals , Discrimination Learning/drug effects , Dopamine Antagonists/pharmacology , Male , Pyridines/pharmacology , Pyrroles/pharmacology , Rats , Rats, Long-Evans , Rats, Sprague-Dawley , Reinforcement, Psychology , Self Administration
15.
Br J Pharmacol ; 164(6): 1652-60, 2011 Nov.
Article in English | MEDLINE | ID: mdl-21501143

ABSTRACT

BACKGROUND AND PURPOSE: The endocannabinoid system appears to play a pivotal role in mediating the rewarding and reinforcing effects of nicotine. Recent studies have shown that the inhibition of fatty acid amide hydrolase (FAAH) attenuates reinstatement of nicotine-seeking induced by nicotine priming and nicotine-associated cues. FAAH hydrolyses the endogenous endocannabinoid anandamide, as well as other non-cannabinoid ligands such as oleoylethanolamide (OEA) and palmitoylethanolamide (PEA). As OEA and PEA can attenuate both nicotine-taking and nicotine-seeking behaviour, the specific role of anandamide remains unclear. In this study, we have tested the selective anadamide uptake inhibitor, VDM11, which elevates anandamide levels without affecting levels of OEA/PEA, on nicotine-taking and nicotine-seeking behaviour. EXPERIMENTAL APPROACH: We used a nicotine intravenous self-administration model in rats to assess the effect of VDM11, given i.p., on nicotine taking using fixed and progressive ratio schedules of reinforcement as well as on reinstatement of nicotine-seeking induced by nicotine priming and nicotine-associated cues. KEY RESULTS: VDM11 did not affect levels of responding for nicotine under fixed-ratio and progressive-ratio schedules of reinforcement. In contrast, VDM11 dose-dependently attenuated reinstatement of nicotine-seeking behaviour induced by nicotine-associated cues and nicotine priming. CONCLUSIONS AND IMPLICATIONS: These results indicate that ligands elevating anandamide levels could have therapeutic value for preventing relapse into nicotine-seeking behaviour and should be tested in humans trying to quit smoking.


Subject(s)
Arachidonic Acids/antagonists & inhibitors , Arachidonic Acids/pharmacology , Behavior, Animal/drug effects , Nicotine/administration & dosage , Polyunsaturated Alkamides/antagonists & inhibitors , Tobacco Use Disorder , Animals , Arachidonic Acids/metabolism , Conditioning, Operant , Drug-Seeking Behavior , Endocannabinoids , Extinction, Psychological , Male , Polyunsaturated Alkamides/metabolism , Rats , Rats, Long-Evans , Reinforcement Schedule , Self Administration
16.
J Pharmacol Exp Ther ; 327(2): 482-90, 2008 Nov.
Article in English | MEDLINE | ID: mdl-18725543

ABSTRACT

Emerging evidence suggests that the rewarding, abuse-related effects of nicotine are modulated by the endocannabinoid system of the brain. For example, pharmacological blockade or genetic deletion of cannabinoid CB(1) receptors can reduce or eliminate many abuse-related behavioral and neurochemical effects of nicotine. Furthermore, doses of Delta(9)-tetrahydrocannabinol and nicotine that are ineffective when given alone can induce conditioned place preference when given together. These previous studies have used systemically administered CB(1) receptor agonists and antagonists and gene deletion techniques, which affect cannabinoid CB(1) receptors throughout the brain. A more functionally selective way to alter endocannabinoid activity is to inhibit fatty acid amide hydrolase (FAAH), thereby magnifying and prolonging the effects of the endocannabinoid anandamide only when and where it is synthesized and released on demand. Here, we combined behavioral and neurochemical approaches to evaluate whether the FAAH inhibitor URB597 (cyclohexyl carbamic acid 3'-carbamoyl-3-yl ester) could alter the abuse-related effects of nicotine in rats. We found that URB597, at a dose (0.3 mg/kg) that had no behavioral effects by itself, prevented development of nicotine-induced conditioned place preference (CPP) and acquisition of nicotine self-administration. URB597 also reduced nicotine-induced reinstatement in both CPP and self-administration models of relapse. Furthermore, in vivo microdialysis showed that URB597 reduced nicotine-induced dopamine elevations in the nucleus accumbens shell, the terminal area of the brain's mesolimbic reward system. These findings suggest that FAAH inhibition can counteract the addictive properties of nicotine and that FAAH may serve as a new target for development of medications for treatment of tobacco dependence.


Subject(s)
Amidohydrolases/antagonists & inhibitors , Arachidonic Acids/metabolism , Benzamides/pharmacology , Carbamates/pharmacology , Conditioning, Psychological/drug effects , Dopamine/analysis , Nicotine/pharmacology , Nucleus Accumbens/drug effects , Polyunsaturated Alkamides/metabolism , Tobacco Use Disorder/drug therapy , Amidohydrolases/physiology , Animals , Endocannabinoids , Hydrolysis , Male , Motor Activity/drug effects , Nucleus Accumbens/chemistry , Rats , Rats, Long-Evans , Rats, Sprague-Dawley , Reward , Self Administration , Tobacco Use Disorder/enzymology
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